Category Archives: Makari Krause

Carbon taxes have long been thought of as the most efficient and successful way to decrease GHG emissions and thereby curb climate change. Marron and Toder (2014) examine some of the challenges associated with this approach to carbon mitigation, namely setting the tax rate, collecting the tax, and using the revenue. In order to internalize the GHG emissions externality one must tax those emissions at a rate that brings the social cost in line with the private cost. This is referred to as the social cost of carbon and is the price of carbon that would maximize social welfare. Theoretically this approach seems ideal but there are many difficulties involved with determining the social cost of carbon. Determining the true economic effects of GHG emissions is quite difficult and requires complex modeling. These models operate on a set of assumptions that are controversial in many cases. Leading to a wide range of estimates for the social cost of carbon with a mean of $196/ton and a standard deviation of $322/ton. Another important question to ask when calculating cost is whether that cost will be evaluated on a global or national scale. The costs of climate change and the benefits of mitigation are global but often US policymakers exclude global considerations. Continue reading →

Our newest book, published on May 6, 2015 and available at Amazon.com for $19.95.

The focus of this book is the interactions between energy, ecology, and climate change, as well as a few of the responses of humanity to these interactions. It is not a textbook, but a series of chapters discussing subtopics in which the authors were interested and wished to write about. The basic material is cutting-edge science; technical journal articles published within the last year, selected for their relevance and interest. Each author selected eight or so technical papers representing his or her view of the most interesting current research in the field, and wrote summaries of them in a journalistic style that is free of scientific jargon and understandable by lay readers. This is the sort of science writing that you might encounter in the New York Times, but concentrated in a way intended to give as broad an overview of the chapter topics as possible. None of this research will appear in textbooks for a few years, so there are not many ways that readers without access to a university library can get access to this information.

This book is intended be browsed—choose a chapter topic you like and read the individual sections in any order; each is intended to be largely stand-alone. Reading all of them will give you considerable insight into what climate scientists concerned with energy, ecology, and human effects are up to, and the challenges they face in understanding one of the most disruptive—if not very rapid—event in human history; anthropogenic climate change. The Table of Contents follows: Continue reading →

As global warming proceeds there will be numerous shifts in plant communities around the world. Blumenthal et al. (2013), realizing that the implications of these shifts are not well known, set about testing how reorganization of plant communities may affect invasive plants. They hypothesize that elevated CO2 levels and warming might strongly influence the success of invasive species in semi-arid grasslands. In order to test their hypothesis they placed Linaria dalmatica, an invasive forb, into grass prairie that was treated with free-air CO2 enrichment and infrared warming. They then measured survival, growth, and reproduction of the forb over a four-year period. The CO2 enrichment had huge effects on the growth and survival rates of L. dalmatica; biomass increased 13 fold, seed production increased 32 fold, and expansion increased seven fold. Warming had little effect. Blumenthal et al. then compared the leaf gas exchange and carbon isotopic composition between L. dalmatica and the native C3 grass, Pascopyrum smithii. The elevated CO2 decreased stomatal conductance in the grass but not in he forb and didn’t increase the photosynthesis rate in the grass nearly as much as it did in the forb. The invasive species benefited hugely from CO2 enrichment, which could have far reaching implications for future colonization. Continue reading →

Ecosystems provide a multitude of services to humans, but one that will continue to grow in importance as climate change progresses is terrestrial carbon storage. In their paper, Bardgett et al. (2013) develop a framework for understanding the multiple mechanisms through which climate indirectly impacts the carbon cycle. These mechanisms are broken into three categories: individual responses, community reordering, and species immigration and loss. Individual responses only include changes to individual organisms without any alteration of the larger communities in which they live. While the individual responses occur in the short term, in the long term (years to decades) observable changes will occur within entire communities. This community reordering involves changes in the abundance of certain species but not the complete extinction of species or the invasion of new species. If the time period is extended even further there will be shifts in species resulting in the invasion of new species and the extinction of old ones. Each of these responses alters interactions between soil and plant communities and has associated implications for the global carbon cycle. Continue reading →

Fossil fuels, while a large part of our energy production, are not a renewable resource and will eventually be depleted. Current climate models, such as the ones used by the IPCC, use levels of future fossil fuel production that Hook and Tang (2013) think are improbable. While fossil fuel combustion currently causes a large part of anthropogenic greenhouse gas emissions, these emissions are linked to fossil fuel production and will decrease as we begin to run out of these resources. There is a multitude of different scenarios that predict future fossil fuel emission and they range hugely in their predictions. The IPCC uses a set of six scenarios called the Special Report of Emission Scenarios (SRES), which are an input for many of their aggregated climate models and influence their conclusions. Hook and Tang question the accuracy of these SRES and aim to review the assumptions that the scenarios make about fossil fuel availability. Continue reading →